Comparative effects of omeprazole, amoxycillin plus metronidazole versus omeprazole, clarithromycin plus metronidazole on the oral, gastric and intestinal microflora in Helicobacter pylori-infected patients

Abstract

Fourteen patients with Helicobacter pylori infection were treated with 20 mg omeprazole, 1 g amoxycillin and 400 mg metronidazole bd for 7 days (OAM), and 16 patients were treated with 20 mg omeprazole, 250 mg clarithromycin and 400 mg metronidazole bd for 7 days (OCM). Saliva, gastric biopsies and faecal samples were collected before, during (day 7) and 4 weeks after treatment in order to analyse alterations of the normal microflora and to determine antimicrobial susceptibility. Both treatment regimens resulted in marked quantitative and qualitative alterations. A selection of resistant streptococcal strains were noticed in both treatment groups, most apparent in the OCM group where a shift from susceptible to resistant strains was recorded. In the OAM group, six patients had overgrowth of resistant enterobacteriaceae during treatment compared with none in the OCM group, in the gastric microflora. The MICs for Enterococcus spp. and Enterobacteriaceae in faeces increased significantly during treatment in both groups. Nine patients in the OAM group became intestinally colonized by yeasts during treatment. The total anaerobic microflora was strongly suppressed in both treatment groups, although most pronounced in the OCM group, where the frequency of clarithromycin-resistant bacteroides strains increased from 2 to 76% during treatment, and remained at 59% 4 weeks post-treatment. Even if the treatment outcome was better in the OCM group (100%) than in the OAM group (71%), the amoxycillin-based treatment might be preferable from an ecological point of view, since the qualitative alterations in terms of emergence and persistence of resistant strains seemed to be most pronounced in the clarithromycin-treated group.

Profiling of bacterial flora in gastric biopsies from patients with Helicobacter pylori-associated gastritis and histologically normal control individuals by temperature gradient gel electrophoresis and 16S rDNA sequence analysis

“…Most of the bacteria identi®ed are normal inhabitants of the respiratory tract and oral cavity and, therefore, it might not be surprising if swallowed bacteria are found in the stomach. Moreover, these results are in good agreement with a recent study revealing the presence and distribution of a gastric mucosal micro¯ora in dyspeptic patients with H. pylori infection [24].…”

Long-term impacts of antibiotic exposure on the human intestinal microbiota

“…The actinobacteria were particularly negatively impacted in both the throat and gut samples immediately after antibiotic treatment, presumably due to clarithromycin that is known to target this group. Adamsson et al (1999) also previously found that this antibiotic treatment regimen led to quantitative and qualitative alterations in the faecal microbiota and suggested that amoxicillin might be better from an ecological perspective than clarithromycin for eradication of H. pylori because it resulted in less emergence of resistant strains.…”

Molecular analysis of the bacterial microbiota in the human stomach

“…However, little is known about other members of the human gastric microbial ecosystem in disease and health. Characterization of the gastric microbiota has traditionally relied on cultivation of gastric juice or mucosal biopsies, and such studies have identified several members of the Firmicutes, Proteobacteria, Actinobacteria, and Fusobacteria phyla, as well as yeasts in relatively low abundance (2,3). The relative paucity of cultivated bacteria and the presence of a harsh local environment have led to assumptions that the human stomach does not harbor a complex microbial biota.…”